The structural core of a design of lifting surfaces comprises a torsion box capable of bearing the aerodynamic and inertial loads that it is subject to. The lifting surfaces are typically designed by means of two lateral parts joined in their plane of symmetry, as in the case of horizontal stabilizers, or two lateral parts and a third central part joining them, as in wings or horizontal stabilizers. A separate case is structures formed from a single box, such as ailerons, flaps, rudders, elevators and vertical stabilizers. The final assembly of lifting surfaces requires the necessary inspection holes (windows, openings or orifices) for adequate access to the attachment zones. Said inspection holes imply an appreciable reduction in the structural efficiency of the zones in their vicinity. This, in turn, implies an increase in weight with respect to an ideal structural configuration.
The attachment of lateral parts is usually done by means of a rib as a whole in its plane of symmetry. This type of installation is possible if the design considers the following aspects:                The lifting surface is provided with fuel tank, which entails access holes (manholes or handholes) in the lower part of the lining in order to carry out assembly/maintenance tasks. Access is also guaranteed with the support of inspection holes in spars or with removable spars. From the viewpoint of the design, manufacture and assembly, each inspection hole or the capacity to dismantle an element implies a major complication. Moreover, each inspection hole implies an increase in the weight of the structure.        The size of the lifting surface is sufficiently small to allow access to assembly operations from the outside.        
We do not know of any integration system for lifting surfaces lateral parts existing in the state of the art like those that have been referred to, in which the conventional in one piece rib mentioned above is replaced with bars forming a truss structure, as is done by the present invention.